1. Field of the Invention
The present invention relates to a lead-free piezoelectric element and a method for manufacturing the lead-free piezoelectric element. The present invention also relates to a liquid ejection head, a liquid ejection apparatus, an ultrasonic motor, an optical device, a vibration device, a dust removing device, an imaging apparatus, and an electronic apparatus, each including the piezoelectric element.
2. Description of the Related Art
Metal oxides having a perovskite structure, such as lead zirconate titanate (hereinafter, referred to as “PZT”), are generally used as piezoelectric ceramics for piezoelectric elements. However, PZT, which includes lead, has a problem in that it causes environmental pollution. Therefore, development of lead-free piezoelectric ceramics is desired.
Barium titanate is a known example of a lead-free piezoelectric ceramic. Materials based on barium titanate have been developed to improve the characteristics of a lead-free piezoelectric ceramic.
Japanese Patent Laid-Open No. 2009-215111 describes a material in which some of A sites of barium titanate are replaced with Ca and some of B sites of barium titanate are replaced with Zr in order to improve the piezoelectric characteristics of barium titanate. This material has a phase transition temperature at a temperature near room temperature and has an improved piezoelectric constant at a temperature near room temperature due to an increase in relative permittivity.
However, this material, which has improved piezoelectric characteristics due to an increase in the relative permittivity, has a problem in that the power consumption of a piezoelectric element made from this material is high.